I find myself using the reference books above virtually every week and daily in the case of the ephemeris and world charts.

The formative books were ones I returned to over and over OR found amazing materials in the first book I read so I proceeded to read all the works by that author(s) (March & McEvers, Greene, O'Howell, Robson, Tyl, Erlewine, Brady)

I still go back and reread books, ALWAYS finding something new that compliments or increases my knowledge. I might have missed it the first time!

Donna Young

This is a great question, and something that's really evolved over time. My go-to books as a beginner were much different than they are now, but if I was to judge purely on how beaten up the books are, the list would likely look something like this:

#1 - An ephemeris. Mine is Rosicrucian, which I prefer because it shows declination. Raphael's does the same, apparently.
#2 - Horoscope Symbols - Rob Hand - Written in 1981, I look forward to a revision reflecting his current thoughts.
#3 - Planets in Transits - Rob Hand - I understand a re-write is in the works for this one.
#4 - Astrology: Understanding the Birth Chart - Kevin Burk. Written as a manual for students to pass NCGR level 1. There are a couple minor errors in my copy but these have probably been corrected. A great student/teaching book.
#5 - History of Horoscopic Astrology - James Herschel Holden
#6 & 7 - Rulership books - I refer to both Rex Bills and Lee Lehman
I also like to see what Marion March & Joan McEvers have to say when I'm exploring a topic

I always use the Book of World Horoscopes by Nicholas Campion to research political events, and I’m glad to say that the computer age did not pull me away from my ephemeris book, which I refer to in every reading.

Wendy Stacey

Besides my ephemeris and Michelson’s Table of Planetary Phenomena which I always have on my desk I frequently refer to the following books; Sue Tompkins Aspects, Nick Campion’s The Book of World Horoscopes and Mundane Astrology, Ebertin’s The Combination of Stellar Influences and Liz Greene’s books on Fate, Saturn, Neptune and the Luminaries. I love Rick Tarnas’ s books for their insight, Frank Clifford’s are always interesting and I also am a rather big Gauquelin fan… I could actually go on for quite a long time…

This July, when Noel Tyl came to Beijing for a 3 day workshop, I was in his teaching assistant group. He said he would know which books one has read or not read yet by the questions one asked! He recommended I read his The creative Astrologer on several occasions. Interestingly, this is the very book I just bought but haven't read yet.

I am reading The Creative Astrologer now. It is more concise and structured compared with 900-page Synthesis & Counseling in Astrology (one of my go-to books), by putting all Noel Tyl's master skill & core teachings together, and emphases on the art part of astrology. It is fascinating.

I am a big reader (moon in Gemini, with a strong Mercury conjunct Pluto) and read very quickly, sometimes I cannot digest thoroughly and just loaded with mountains of information. When reading The Creative Astrologer, my running thoughts can really pace down, dive in and enjoy every page I read. It is definitely a book one can read several times and always get inspired!

Aubrie De Clerck

There are so many books that I use and love, it is hard to choose. Here are some that stand out to me:

The Complete Book of Spiritual Astrology - Per Henrik Gullfoss (just love this as a general interpretation book, very insightful)
Astrology for the Soul - Jan Spiller (excellent for clients interested in purpose and roadblocks that may keep them from fully discovering it, written very accessibly)
Chiron and the Healing Journey - Melanie Reinhart (very complete look at Chiron by sign, house, aspect and transit)
Astrology of Self Discovery - Tracy Marks (excellent inquiries for outer planet transits)

Arlan Wise

I think the ephemeris is the most important book I own.
I use Astrological Gardening by Louise Riotte and The Daily use of the Ephemeris by Elizabeth Aldrich when I write my monthly column.
I think that all of Dane Rudhyar's work was my foundation. I like all of Liz Green's and Richard Idemon's books. I refer to Robert Jansky's Interpreting the eclipses. I use Jane Ridder-Patrick's Introduction to Medical Astrology as a reference book. I think Michael's Lutin work is brilliant.

These are but a few of the books that have been inspiring and influential.

David A Zimmerman

Yes thank you for asking this question on the important books we study...............For me the life's work of Dr. Douglas Baker has been the most important.

I am a student of the esoteric sciences and a member of the Theosophical Society, both here in America and also in England......A long time student of Alice A. Bailey and the writings of D.K. (The Tibetan )........His Dictionary of Astrology (3 Volumes) is the finest aid to understanding Esoteric Astrology in the World...

Also his numerous books on esoteric astrology some 50 in total I believe have no comparison...........I have found the accuracy of the charts I do based on guidance from Dr. Baker's books to be the most helpful........The detail of each sign and house is beyond compare, as well as his understanding of all aspects of Esoteric Astrology......................

Lutia Lausane

Having just graduated from The Complete Course with Maurice Fernandez, I rely heavily on his Neptune book, and on his book Astrology and the Evolution of Consciousness. I am becoming familiar with The Mountain Astrologer publications and of course often turn back to Cosmos & Psyche by Richard Tarnas. I also refer to Jim Maynard’s Celestial Guide on a daily basis. Looking forward to hearing what resources others use. I also daily use daily analysis of dreams, and from a Jungian perspective. Many layers!

Vinnie Scotti

My sun and moon are tied up in an air grand trine, Gemini a synthesis of contradictions, Libra multi perspectives and Aquarius = Astrology. So I tend to gravitate towards the books that shed a whole new light on astrology, Martin Goldsmith's work riddled with it iconoclastic take on astrology and its complete departure from the familiar cook book definitions of the zodiac really gets me going. But I have not read any Rudhyar for a while, but I hope through my practicing of astrology I use his work as a constant reference, not that he departed from the norm like goldsmith per say but he put across in his literature this idea that maybe people born in the southern hemisphere could possible be the opposite sign, for example I was born Oct. 9th with this idea if I was born in Cape Town I would be an Aries. I'm not saying this idea is gospel but it shifts the mind into the unknown yet to be discovered vistas of astrology.

Laurie Naughtin

I am really enjoying a recently purchased book by Naomi Bennett. Foundations of
Astrology.
It is challenging the way I think about astrology. As for Capricorn energy she
mentions the tendency one has to give in to our oppressors as well as to conform to
our environment.
Be good, save and be thrifty, curb your appetite and do the unpleasant things in life
because they have to be done.
With the new Moon it is the time to be the Goat and rise to higher places, turn away
from the quick fixes and easy profits. Any promises that are unsound with profits that
are improbable, this Capricorn new Moon will allow us to see the negative properties
that can block out new and more favourable possibilities.
This Capricorn Moon can help us take a dark view of the future, to be sound and
practical, to judge the future by the past.
I have applied her views and adapted to a new Moon situation. After all the Moon is
in her detriment in Capricorn.
The way Naomi looks at the houses and rulers after many years of research in Egypt
studying what has been handed down to the Hellenistic Greeks and filling in the
missing pieces makes for fascinating reading.

A recent book that has deeply influenced me, primarily due to one essay (there
are other excellent essays too; this one has just been profoundly helpful to me
personally ) is: Transpersonal Astrology: Explorations at the Frontier. The specific essay is:
"Locational Astrology: A Transpersonal Perspective" by Andrew Smith.

Also, important to me are the following two books, which I was introduced to in a Moon Intensive with Steven Forrest. I don't refer to them a lot, but they were very important to me at the time I received them (11 or 12 years ago) and I re-read parts of them from time to time to deepen my understanding and reinforce knowledge I need to remember, as well as to again and again, get a feel for "where I am with it all" with my own moon phase.

Dawn Glinski
The Astrological Thesaurus (Book1) by Michael Munkasey was a great book for helping me learn the houses of the natal chart more thoroughly. It has assisted me in providing more accurate interpretations both natally and with the transits and progressions.

Dmitriy Paramonov

I try not to keep paper books in my house. I prefer eBooks. This is my little contribution to protection of the environment. Therefore, there are not many books on my bookshelf. However, there are many electronic devices that allow me to get information.
The main content of my bookshelf various encyclopedias, dictionaries and reference books as it really helps me in my work.
I like Dane Rudhyar’s books. This author reveals the depth of astrology. Rudhyar takes reader by fatalism and opens the way to freedom, the path of the evolution of consciousness.
When a beginner astrologer approaches and asks me to recommend books I always advise Marion D.March & Joan McEvers The Only Way To Learn Astrology. This is series of books which is available in the form of talks about all the highlights in Astrology.

Ellen Zucker

Favorite Astrology reference books… There are so many. I would list my annual Celestial Guides by Jim Maynard, generally in appointment book form and my ephemerides at the top of the list. Beyond those it depends on the need. Georgia Stathis Business Astrology 101 is excellent on general business astrology topics but also basic astrology. Bruce Scofield’s book on electional astrology is my go to source for questions in that area. Llewellyn George’s A to Z Horoscope Maker is a good source for basics. Rex Bill’s Rulership book and Lee Lehman’s book on rulerships helps me answer this questions.

Susan Minahan

Astrology books have inspired me endlessly. I still have a bunch on my shelf yearning to be digested, or at least introduced. Even the titles or authors spur inspirational quests of thought, about the concepts presented by subject or through the astrologer's perspective.
In "my beginning", like many, I devoured Linda Goodman's Sun Signs. It gave the first viewpoint that signs are energetic tools, applied in a variety of ways in our experience in life by expanding astrology's relationships, to our own personal nature, our romance, our career, our family. Grant Lewis’ Heaven Knows What widened the focus with sun-moon combinations, and planetary aspects. Suddenly, astrology became a complexity, expressing characteristics that relied upon our individualism. However, these were cookbook-oriented resources, and though these fascinating sources clearly identified how people's nature's varied, it was Dane Rudhyar's The Astrological Houses, The Pulse of Life, and Directives for New Life that clarified the conceptual rhythms of astrology that orient how it ticks. Rob Hand's Transits gave further awareness to me how the role of astrology continues in every moment of our lives. MB Cook’s Astrology Plus:the signs and houses specified the chart's angles and emphasized the chart's patterns, explained as karma, due to past life, which added to the depth, but I needed to grasp my own idea of our spiritual connection in this life, to learn the whys.

So, over the past six years since I've returned to study and incorporate astrological significances to interpret myself, I was first impressed with Jeffrey Green's Pluto Vol I and Vol II books that distinctly illustrate the change people aspire in their lifetime involuntarily due to their soul's need to grow. This was vital information, because it gave astrology purpose as a laser insightful mechanism, an artful scientific biological entity. Then, I read K'abbalist Rav P.S. Berg's Kabbalist Astrology that aligns the vital importance of the lunar nodes, to illustrate as a chapter puts, "cracking the code of the soul". It added life's purposeful meaning because astrology related to our soul's spiritual life and growth.

Recently, I've found Maurice Fernandez's Astrology and the Evolution of Consciousness most insightful because of how the book gives a perspective of the motives of the sun and the moon, and the consequences of the signs in relationship to the luminaries, and the houses they share with those archetypal energies. I love the focus on archetypes.

Greek and Roman myths influenced me tremendously. I find great insight through the different stories and the psychology of the myths behind the archetypes of gods, goddesses and various mortal encounters because they all shed light on factions of our soul's experience like we too each find our way and path.

Besides reading, I study the ephemeris and that's how I chose to write today, when I saw that Transiting Venus and Saturn are 11 degrees Sag, and both directly opposite my natal Mercury 11 Rx Gemini in the 9th house. Mercury is my final depositor and it does work to bridge my spirit and mind and figure out life's soulful philosophy.